The self-cleaning screens belong to a screen group specially developed to be used when the material to be passed can block up the holes of a conventional one.
These are very efficient for sieving material of difficult classification, which are recommended for wet material, agglomeration and drainage.

HARPA TYPE SELF-CLEANING SCREENS, for sieving wet, flake old splinter or agglomerant material. The reason we recommend the harp type self-cleaning screens is that they provide a larger opening than other ones, by allowing the wires to oscillate freely, preventing the openings from blocking up. For best results, we recommend that the HARPA SCREENS are always tensioned (attached) with bigger mesh perpendicular to the flow.

The Veno or Serpa-type self-cleaning screens, are not recommended for sieving flake old splinter material, but they guarantee efficiency when used for sieving material that can block the meshes for its large amount of “coal fines”, high level of moisture and for particles of critical sizes. The Veno or Serpa type self-cleaning screens are both efficient in sieving, and the differences between each other are as follows:

	VENO SCREENS: triangular-shaped meshes made of straight and wavy wire. The straight one is slightly bigger in diameter than the wavy one so that during sieving the wires can oscillate differently, which avoid blockage of the meshes. They last slightly longer than the SERPA SCREENS, with a slight reduction of open area.

SERPA SCREENS: have square-shaped meshes of equal dimensions and are woven in parallel at a defined distance owing to the mesh and the wire, ensuring flexibility and independence of each wire and promoting self-oscillation in sieving. They last slightly longer than the VENO SCREENS, with slight increase in the open area.

When the self-cleaning screens are used for very abrasive materials, we recommend that the wefts wires for tying are covered with POLYURETHANE, so as to prolong the duration of the sieve.

It is important that the tying wefts or the polyurethane coverings coincide with the longer, supporting “deck” of the sieve, thereby avoiding premature wear of the screens.